I have just had a quick look at theSumatron Instruction Manual (copy attached).
It is clear from this that the Sumatron device is relatively simple compared
with both our MYG-RSO units.

2. In particular, it is necessary for the operator to adjust 2 potentiometers to
obtain identical traces at each end of the rotor winding (the MYG-RSO units
do this automatically). It is fairly easy to make this adjustment whenthe rotor
winding is perfect, but if there are faults or other problems in the winding,it
can be difficult to judge when the potentiometers have been balanced correctly.

3. Also, I think Sumatron use simultaneous injection of pulses from each end of of
the rotor winding. This explains why they have to use short pulses, otherwise
they would get superimposed pulses displayed on the oscilloscope channels.
In complete contrast, in the preferred mode of operation, the MYG-RSO units
use an alternate pulse excitation arrangement, where the excitation pulses are
injected at each end of the rotor winding alternately and at a high repetition
rate (up to 1000 times per second) using an electronic switching network.

4.This allows the use of longer,higher-energy pulses and also ensures that different
oscilloscope traces cannot be obtained as a result of operator error.
A futhur difference between the Sumatron equipment and the MYG-RSO units is that we
supply a demonstration delay line with each of our systems so that users can
both check that the equipment is working correctly in the absence of an
available rotor winding and also see the effects of applied simulatedinter-turn
and earth faults on the RSO waveforms.